Atomic Scale Sliding and Rolling of Carbon Nanotubes

TL;DR

This paper investigates atomic-scale interactions and friction of carbon nanotubes on graphite surfaces, revealing unique orientations, energy scaling, and differences between sliding and rolling behaviors through molecular simulations.

Contribution

It introduces detailed atomic-scale analysis of nanotube motion, highlighting the energy landscape and friction characteristics for sliding and rolling.

Findings

Nanotubes have unique equilibrium orientations with sharp energy minima.

Sliding has higher energy barriers than rolling.

Rolling can occur with friction comparable to sliding.

Abstract

A carbon nanotube is an ideal object for understanding the atomic scale aspects of interface interaction and friction. Using molecular statics and dynamics methods different types of motion of nanotubes on a graphite surface are investigated. We found that each nanotube has unique equilibrium orientations with sharp potential energy minima. This leads to atomic scale locking of the nanotube. The effective contact area and the total interaction energy scale with the square root of the radius. Sliding and rolling of nanotubes have different characters. The potential energy barriers for sliding nanotubes are higher than that for perfect rolling. When the nanotube is pushed, we observe a combination of atomic scale spinning and sliding motion. The result is rolling with the friction force comparable to sliding.